The present invention relates to a method of retaining a vehicle on an inclined roadway and when starting uphill, wherein the brake force on individual or on several vehicle wheels, in particular, on the wheels of one axle is generated, namely maintained, increased and decreased again, in consideration of the vehicle speed, the brake pedal application, or corresponding criteria. Arrangements for implementing the method are also covered by the present invention.
Inadvertent rolling of a vehicle on an inclined roadway is prevented, and starting uphill is facilitated, even for an unskilled person, by such retaining aids or retaining systems, which are referred to as `hill holders`. Retaining systems of this type enhance the comfort and prevent crashes caused by inattentiveness, clutch damages due to operator errors, etc.
German patent No. 34 39 067 discloses an arrangement for arresting a pressure-fluid-operated wheel brake wherein components of the brake system, which are per se provided for anti-lock control, are used to retain the vehicle. When the brake pedal is released, the braking pressure in this prior art arrangement is reduced only to a predetermined residual pressure which is sufficient to retain the vehicle. To release the wheel brake, a multi-way valve inserted into the pressure fluid path is switched to open on command of a signal issued by the driver or responsive to the driving behavior of the vehicle or the rotational behavior of the wheels.
German patent application No. 40 23 705 describes an arrangement for retaining a vehicle when starting uphill which has an electrically operable actuator that acts by way of a linkage or a Bowden cable on the parking brake of the vehicle. The associated electronics for controlling the actuator is provided with input signals of wheel sensors and switches coupled to the accelerator pedal, the transmission, the clutch, etc.
An object of the present invention is to provide a method which makes it easier to the driver to retain the vehicle and start uphill in various situations. As the situation may be, the method shall intervene in the brake system in the suitable fashion.